Colonoscopy vs. At-Home Test: Understanding the Differences

Pro­tect­ing your­self from colon can­cer starts with screen­ing, and for most, that should begin at age 45. While you have choic­es, colonoscopy stands out as the most effec­tive tool. It not only detects can­cer ear­ly but can actu­al­ly pre­vent it. Adam Nie­mann, MD, a Gas­troen­terol­o­gist at Quin­cy Med­ical Group, explains why colonoscopy remains the gold stan­dard and clar­i­fies the dif­fer­ences between com­mon screen­ing methods.

Two Screen­ing Options: Stool-Based At-Home Tests vs. Colonoscopy

There are two main types of colon can­cer screen­ing tests: colonoscopy and stool-based at-home tests. While at-home tests are an option for some, they are not a replace­ment for colonoscopy — espe­cial­ly for those at high­er risk.

Stool-Based At-Home Tests

Stool-based tests like Colo­guard are becom­ing more com­mon for colon can­cer screen­ing because they are non-inva­sive and easy to use. How­ev­er, their abil­i­ty to detect can­cer and pre­can­cer­ous polyps is limited.

“Colo­guard looks for DNA changes and blood mark­ers in the stool,” explained Dr. Nie­mann. ​“A pos­i­tive result could indi­cate the pres­ence of col­orec­tal can­cer or pre­can­cer­ous polyps and should be fol­lowed up with a colonoscopy.”

Colo­guard is only designed for indi­vid­u­als at aver­age risk — those with­out symp­toms, no fam­i­ly his­to­ry, and no his­to­ry of pre­can­cer­ous polyps. ​“If some­one has had pre­can­cer­ous polyps in the past, Colo­guard is not an approved screen­ing option for them,” Dr. Nie­mann added.

Colonoscopy

While stool-based tests offer con­ve­nience, a colonoscopy pro­vides a more com­pre­hen­sive approach to colon can­cer screening.

“A colonoscopy is the most thor­ough test avail­able,” said Dr. Nie­mann. ​“Not only does it help us detect can­cer, but it also allows us to find and remove pre­can­cer­ous polyps — pre­vent­ing can­cer before it even starts.”

Dur­ing the pro­ce­dure, a thin, flex­i­ble tube with a cam­era is insert­ed into the colon to exam­ine for abnor­mal growths. Per­formed under seda­tion, a colonoscopy allows doc­tors to remove any polyps imme­di­ate­ly, offer­ing both detec­tion and treat­ment in real time. This dual ben­e­fit makes it the pre­ferred screen­ing method.

Reg­u­lar colono­scopies play a cru­cial role in reduc­ing the risk of colon can­cer. ​“The risk of dying from colon can­cer has been shown in stud­ies to decrease by at least 50% with colonoscopy, like­ly more,” said Dr. Niemann.

Under­stand­ing Your Screen­ing Needs

Dr. Nie­mann encour­ages those who are due for a colon can­cer screen­ing to take action. ​“Colonoscopy is one of the few screen­ing tests where we not only can find can­cer ear­ly but also hope­ful­ly pre­vent it from hap­pen­ing in the first place,” he said. 

If you have ques­tions about your screen­ing needs, speak to your pri­ma­ry care provider. To sched­ule your screen­ing, or for more infor­ma­tion, call the QMG Gas­troen­terol­o­gy depart­ment at 217−222−6550, ext. 3636 or vis­it quin​cymed​group​.com/​colon.